Stapling device



June 24, 1941.

R. VANCURA 2,246,647-

STAPLING DEVICE Filed Dec. 10, 1938 In ventar Rudolf Vancur'a y W M Attorney.

Patented June 24, 1941 STAPLIN G DEVICE Rudolf Vancura, Vienna, Germany, assignor to the firm Reissnigelund Metallkurzwarenfabrik Heinrich Sachs, Vienna, Germany Application December 10, 1938, Serial No. 244,995

4Claims.

This invention relates to stapling devices with a full-stroke mechanism for the staple-driving plunger. In the known stapling devices the fullstroke mechanism consists of coacting elements, suchas for instance teeth and pawls provided on the plunger and its housing, respectively, and adapted to arrest the plunger on its downstroke, so as to prevent the plunger from being restored to its initial position by its return spring before the plunger has completed its downstroke and expelled from the vertical guideway the foremost staple detached from the row of staples inserted in the device. In this manner a safeguard is provided against the possibility of two or more staples being driven at a time into the guideway and blocking the latter.

In the known types of the full-stroke mechanisms there are provided, for restoring the pawl into the position of rest, either spring-loaded releasing latches or accurately machined positive guiding elements, such as cam grooves or the like. These mechanisms are thus comp ed of a number of parts and moving elements which must be of small size owing to the small space available for their accommodation in the plunger housing and extremely accurately turned out or machined and which necessitate time-consuming work for their'assembling. These types of fullstroke mechanisms are thus complicated and expensive, without actually providing a reliable safeguard against trouble in connection with the operation of the stapling device. Should trouble arise the users of the machines, whoare not skilled mechanics, after having dismantled the complicated full-stroke mechanism, will find it extremely diflicult or even impossible to reassemble it.

In contrast thereto, the full-stroke mechanism provided by the present invention is thoroughly simple in construction and assembly. This mechanism consists of a lug on the plunger and a loose raclemovable or guided in the plunger housing transversely thereof. This rack is normally obliquely set, either by means of oppositely acting springs bearing against the ends thereof,

or by having its upper end portion bent at an obtuse angle to the remainder and pressed by a spring against one side of the housing, and is further furnished with an aperture above the uppermost tooth through which the lug on the plunger may pass. As will be described in due course, at the down-stroke of the plunger the rack is pivotally moved by the lug about its upper end, while at the up-stroke oi the plunger the rack is pivotally moved about its lower end 'for the sake of clarity, in the accompanying drawing, in which:

Fig. 1 is a sectional elevation as seen from the side,

Fig. 2 a sectional elevation as seen from the rear end,

Fig. 3 is a cross-section-on the line A-B of Fig. 1,

Fig. 4 is a diagrammatic elevational view of the arresting means in one operative position,

Fig. 5 is an elevational view of the arresting means in another operative position, the broken lines representing a position of the arresting means on the return movement of the plunger, and M Fig. 6 is an elevational view of a modified form of the arresting means illustrating several different positions thereof.

Referring to Figs. 1 to 3, the staple-driving plunger a is provided on its rear face with a lug b formed for instance by an extension of the screw d by means of which the driver member c is secured to the stem of the plunger. The rack associated with the lug b is loosely mounted or supported in the plunger housing, between the two vertical side cheeks f pertaining to the plunger guiding means; but the rack is guided for movement in a plane at right angles to the movement of the lug on the plunger, by means of two guide rods 0 which pass through apertures g in the rack. The rack is bent at an obtuse angle and the lower part e is provided with arresting teeth and gaps, while the upper part E is pressed against one side of the plunger housing by a spring h counter-supported against the other side of the housing. The spring h is helically wound around the upper guide rod g, so that in the position of rest the part e of the rack is obliquely disposed with respect to the side memher i and extends with its lower end angularly across the path of movement of the lug b. Above the uppermost tooth the rack is provided with a suitable aperture or gap i for the reception of the lug b.

Should the plunger a, for any reason not make a complete downward stroke, to completely drive the staple out of the driveway the plunger is prevented from returning to its full upward position. When the plunger a is moved downwardly the teeth on the rack will be deflected by the lug b, and should the downward movement of the plunger be discontinued before the plunger has reached the full limit of its downward stroke. upward movement of the plunger will be prevented by engagement of the lug b with the teeth on the rack, as clearly illustrated in Fig. 4.

The lug may instead of being arranged at the back side of the plunger be arranged at the front side; in this case the rack in the casing is arranged before the plunger.

On complete depression of the plunger the lug b, after deflecting the rack to the requisite extent, reaches the lower end of the rack as shown in full lines in the diagrammatic Fig. 5, in which for the sake of clearness the teeth of the rack have been omitted. Thereupon the rack is immediately restored into the normal position by the spring h pressing against the upper part E, in which position the lower end of the rack is on the opposite side of the lug (this position being shown in dotted lines in Fig. 5). In ascending, on its return movement with the plunger, the lug b then acts upon the rear side of the rack, pressing the same bodily to one side (in the present instance towards the right), Fig. 5, by compressing the spring h, into the position shown in broken lines in Fig. 5, until the lug reaches the gap 1' in the rack, which enables the rack to be restored by the compressed spring h, past the lug, into the initial position. The plunger is then ready for the next operating cycle. In its move-, ments the rack is guided on the rods g.

In contrast to the hitherto known arresting means for the staple-driving plungers of stapling devices the arresting means according to the present invention comprise, as will be seen, apart from the lug on the plunger, merely a single moving part, namely the movably mounted rack which is shaped and adapted to be both pivotally movable and laterally displaceable.- A further advantage ofthe present invention is that the rack is guided between the housing walls along guide elements attached thereto, and can thus not be removed when the device is taken apart for cleaning or other purposes; and thus does not require to be re-assembled, whereas the arresting means hitherto known have to be removed from the device when the device is dismantled.

The rack, as shown in Fig. 3, may have a crosssection like an angle-bar consisting, on the one hand, of a flange e' disposed at right angles to the lug b and provided with the teeth and the gap '2', and, on the other hand, of a flange e" provided with the apertures g for the two guide rods 9. A rack of this angle-bar type is of light weight and yet sufficiently rigid.

ames? end pressing in a direction opposite to the upper spring .3 (Fig. 6). On the downstroke of the plunger 71. the lug p operates the rack in the manner already mentioned. As soon as the lug 1) has reached the lower end of the rack (shown in dotted lines in Fig. 6) the rack is immediately restored into the normal position (towards the right) by the compressed spring m. The lug :2 now ascending on its return movement (with the plunger) finally acts upon the rear side of the rack (shown in. broken lines in Fig. 6) and rocks the rack about its lower end as a fulcrum. When the lug 3) reaches the gap in the rack the compressed spring s moves the rack to the initial position.

The vertical facing plate 7' of the housing is suitably provided with two rearwardly extending vertical side cheeks f leaving between them a middle slot 76 of the breadth of the plunger and guiding the plunger which is disposed at the covering plate I. Thus the plunger a and the rack are arranged in a casing which is open at the rear side for inspection, in case the mechanism should happen to get out of order, and for lubricating the movable parts.

I claim:

1. In a stapling device, a plunger, a plunger housing, means to arrest the upward movement of the plunger before the completion of a full fastener driving stroke, said means comprising a lug extending from the rear face of the plunger, a rack positioned obliquely in the housing and to the path of travel of said lug, said rack supported by two rods secured to the housing, a

As already mentioned, instead of a rack springstressed at the upper end there may also be used a rack q stressed not only by a spring 3 at the upper end but also by a spring m at the lower spring for pressing the upper end of said rack against one side of the housing, said rack having an opening for the passage of said lug, downward movement of said plunger moving said lug against the force of the spring to displace said rack, and return movement of said plunger after a complete driving stroke displacing said rack in the opposite direction until the said rack is released by the passage of said lug through the opening in said rack to restore said rack to its initial position.

2. A stapling device according to claim 1, wherein the rack comprises an L-shaped section. one flange oi which is disposed in the path of the lug and provided with teeth and said opening.

3. A stapling device according to claim 1, wherein besides the spring at the upper end of the rack a spring at the lower end is provided directing its force opposite to the direction of force of the upper spring.

4. A stapling device according to claim 1, wherein the plunger housing is provided with a facing plate and with two rearwardly extending vertical side cheeks leaving between them a middle slot of the breadth of the plunger as a guideway for the plunger.

RUDOLFVANCURA. 

